As is known, vehicle wheels generally comprise a metal rim with ring-shaped turn-ups that are arranged on the outer circular edge and which act as an adherent stop for the beads of an elastic tire.
The use is also currently known of so-called “tire changing” machines for removing and fitting tires from and onto their relevant rims for carrying out, for example, inner tube maintenance, repair or replacement jobs.
These tire changing machines are essentially composed of a base frame which supports a series of tools needed to fit and remove the tire.
The tools on traditional tire changing machines are usually of two types: bead breaking tools, for insertion between the tire beads and the corresponding ring-shaped turn-ups of the rim to detach these, and extraction tools, also called “claws”, having a curved end part suitable for fastening onto the tire beads and moving these away from the relevant rim.
Use of the tools on the wheel occurs while this is rotated on special clamping and rotating device for clamping and rotating the wheel rim.
The rotation axis defined by the clamping and rotating device can be vertical or horizontal.
The tire changing machines with vertical rotation axis usually have a vertical spindle fitted on the base frame in a fixed way, and a series of tool supporting arms that can be moved closer and away from the wheel depending on the size of the rim and the tire.
The movement of the supporting arms occurs along radial approach and away movement directions with respect to the wheel centre and, therefore, without substantially changing the position of the tools with respect to the rim; both the bead breaking tools and the extraction tools, in fact, are turned towards the wheel centre whatever the diameter dimensions of the rim.
The tire chaining machines with horizontal rotation axis on the other hand have a horizontal spindle fitted on the base frame in a moving way along guide means, mostly vertical.
In this type of machine, the extraction tool is kept suspended at a pre-established height and is positioned on the vertical position plane of the horizontal rotation axis; depending on the diameter dimensions of the wheel, consequently, the rim fitted on the spindle is moved closer to and away from the extraction tool.
The bead breaking tools, on the other hand, are fitted on specific arms positioned obliquely with respect to the vertical position plane of the rotation axis.
These traditional tire changing machines with horizontal rotation axis have a number of drawbacks including the fact that they are not always functional and practical to use.
In this respect, it must be noted that the lowering and lifting of the spindle often results in the rotation axis and the supporting arms being crooked.
This results in incorrect operation of the bead breaking tools which, on the contrary, are designed to operate correctly in a position in which the relevant supporting arms are positioned at right angles and incident to the spindle rotation axis.
The work done on the wheel beads can therefore be difficult and irregular, and can cause excess deformations and/or defects to the tire and the bead breaking tools.